title: Leishmania infantum expresses a mitochondrial nuclease homologous to EndoG that migrates to the nucleus in response to an apoptotic stimulus.
abstract: It is increasingly accepted that single-celled organisms, such as Leishmania parasites, are able to undergo a cell death process that resembles apoptosis in metazoans and is induced by a variety of stimuli. However, the molecular mechanisms that participate and regulate this death process are still very poorly described, and very few of the participating molecules have been identified. Because DNA degradation is probably the most frequently characterized event during programmed cell death in Leishmania parasites, we have focused on identifying a candidate nuclease responsible for this effect during the cell death process. The results presented herein demonstrate that Leishmania infantum promastigotes express a nuclease similar to the endonuclease G of higher eukaryotes which, according to its predicted structure, belongs to the beta beta alpha metal superfamily of nucleases. Its cation dependence resembles that of the EndoGs present in other organisms and, similarly to them, it is inhibited by moderate concentrations of K+ or Na+. L. infantum EndoG contains a signal peptide that causes its translocation to the mitochondrion where it is maintained under normal growth conditions. However, under the pressure of a death stimulus such as edelfosine treatment, L. infantum EndoG is released from the single mitochondrion and translocates to the nucleus, where it is thought to participate in the process of DNA degradation that is associated with programmed cell death. Our results also demonstrate that overexpression of the nuclease in edelfosine-treated promastigotes causes a significant increase in the percentage of TUNEL-positive parasites.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Campus Universitario, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Rico
authors.forename: Juan Fernando
authors.initials: JF
authors.lastname: Alzate
authors.forename: Andrés Augusto
authors.initials: AA
authors.lastname: Arias
authors.forename: David
authors.initials: D
authors.lastname: Moreno
authors.forename: Joachim
authors.initials: J
authors.lastname: Clos
authors.forename: Federico
authors.initials: F
authors.lastname: Gago
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Moreno
authors.forename: Mercedes
authors.initials: M
authors.lastname: Domínguez
authors.forename: Antonio
authors.initials: A
authors.lastname: Jiménez-Ruiz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D002467:Cell Nucleus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D003851:Deoxyribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D018314:Leishmania infantum / Q000737:chemistry / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D008928:Mitochondria / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D021382:Protein Sorting Signals; D015800:Protozoan Proteins; D003851:Deoxyribonucleases; D004706:Endodeoxyribonucleases; C052391:endonuclease G